With a known clamping handle of this kind, the clamping element is formed by segment-like clamping jaws of the screw head. In order to be able to exert a radial pressure on these clamping jaws, the screw head and a screw nut must be developed conically (DT-PS 929 867). For reasons of strength, the clamping jaws should not be too weak. Their deformation, for clamping the instrument therefore requires a strong tightening of the screw nut. This in return results later in the screw nut often not being able to be loosened with bare fingers. On the other hand, a screw joint which is too slack does not guarantee a tight fit of the instrument. Furthermore, the development of clamping jaws and a threaded cone on a relatively small working part makes the known clamping handle complicated and expensive.